Why is the diameter of the inlet so small compared to the outlet?
The reason is that we needed closed area inside the impeller for building up the pressure, still we did not want to increase the outside of the impeller (more motor power needed). Small inlet typical for high pressure fans. The outlet is designed as a medium pressure fan to be able to reach as high air volumes as possible. Remember this fan is made to handle under pressure, so we wanted to decrease the pressure loss at the outlet as much as possible.
